I am looking to implement a HA redis implementation using Master-Slave redis servers. The web servers will connect to these through an HAProxy instance installed on each box.

The situation is easy with only two servers, if one goes down the other has to be made the new master. But what about when there are more than one slaves and either one of the remaining slaves can be promoted to master? I know redis sentinel has a notification mechanism in the event of a failover but how do I use it to interact with the HAproxy's on each of the web servers and tell them which server is the new master?